Method of forming carbon layer and method of forming interconnect structure

ABSTRACT

Provided are a method of forming a carbon layer and a method of forming an interconnect structure. The method of forming a carbon layer includes providing a substrate including first and second material layers, forming a surface treatment layer on at least one of the first and second material layers, and selectively forming a carbon layer on one of the first material layer and the second material layer. The carbon layer has an sp2 bonding structure.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2020-0110588, filed on Aug. 31,2020, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated by reference herein in its entirety.

BACKGROUND 1. Field

The present disclosure relates to methods of forming a carbon layerand/or methods of forming an interconnect structure by using a carbonlayer as a mask.

2. Description of Related Art

For high integration of semiconductor devices, the size of semiconductordevices may gradually decrease, and in accordance with this, a linewidth of wirings in an interconnect structure also may be reduced to ananoscale.

To form a nano-scale wiring, a photolithography process fornano-patterning may be performed, and in this case, misalignment oroverlay, or the like may occur. Recently, in order to address the aboveissue, a fully-aligned via (FAV) integration process may be used.

SUMMARY

Provided are methods of forming a carbon layer and/or methods of formingan interconnect structure by using a carbon layer as a mask.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of the presented embodiments of the disclosure.

According to an embodiment, a method of forming a carbon layer mayinclude providing a substrate including a first material layer and asecond material layer; forming a surface treatment layer on at least oneof the first material layer and the second material layer; andselectively forming a carbon layer on one of the first material layerand the second material layer. The carbon layer may have an sp² bondingstructure.

In some embodiments, the selectively forming the carbon layer mayinclude selectively forming the carbon layer on a hydrophobic surface ofthe first material layer or a hydrophobic surface of the second materiallayer.

In some embodiments, the carbon layer may include intrinsic graphene,nanocrystalline graphene, or graphene quantum dots (GQD).

In some embodiments, the forming the surface treatment layer may includeforming the surface treatment layer as a self-assembled monolayer (SAM).

In some embodiments, after the forming the surface treatment layer, adifference between a water contact angle (WCA) of the first materiallayer and a WCA of the second material layer may be 50 degrees orgreater.

In some embodiments, the surface treatment layer may include at leastone of forming a hydrophobic surface treatment layer on one of the firstmaterial layer and the second material layer, and forming a hydrophilicsurface treatment layer on an other of the first material layer and thesecond material layer.

In some embodiments, the hydrophobic surface treatment layer may includean organic material including a hydrophobic functional group.

In some embodiments, the hydrophilic surface treatment layer may includean organic material including a hydrophilic functional group. Thehydrophilic functional group may include a functional group capable offorming a hydrogen bond.

In some embodiments, the first material layer may include a metal, andthe second material layer may include an insulator or a semiconductor.

In some embodiments, the selectively forming the carbon layer may beperformed using deposition, transfer, or solution coating.

In some embodiments, the method may further include selectively forminga third material layer on the first material layer or the secondmaterial layer. The third material layer may be formed on the one of thefirst material layer and the second material on which the carbon layeris not formed.

According to an embodiment, a method of forming an interconnect mayinclude providing a substrate including a first metal layer and a firstinsulating layer; forming a surface treatment layer on at least one ofthe first metal layer and the first insulating layer; and selectivelyforming a carbon layer on the first metal layer, the carbon layer havingan sp² bonding structure; selectively forming a second insulating layeron the first insulating layer; forming a third insulating layer to coverthe second insulating layer; and forming a second metal layer after theforming the third insulating layer, the second metal layer beingelectrically connected to the first metal layer.

In some embodiments, the carbon layer may include intrinsic graphene,nanocrystalline graphene, or GQDs.

In some embodiments, the first insulating layer may include a dielectricmaterial having a dielectric constant of 3.6 or lower.

In some embodiments, the carbon layer may have a contact angle of about60 degrees to about 110 degrees.

In some embodiments, the carbon layer may further include F, CL, Br, N,P or O atoms.

In some embodiments, the second insulating layer may include Al₂O₃, AlN,ZrO₂, HfO_(x), SiO₂, SiCO, SiON, SiCN, SiCOH, AlSiO or BN (BoronNitride).

In some embodiments, at least a portion of the carbon layer may remainon the first metal layer after the forming the second metal layer.

In some embodiments, the method may further include removing a portionof the carbon layer or all of the carbon layer.

According to an embodiment, a method of forming a carbon layer mayinclude forming a surface treatment layer on a substrate including afirst material layer and a second material layer, and selectivelyforming a carbon layer on the first material layer and not the secondmaterial layer. A material of the first material layer may be differentthan a material of the second material layer. The surface treatmentlayer may be formed on the first material layer. The carbon layer mayhave an sp² bonding structure.

In some embodiments, the carbon layer may include intrinsic graphene,nanocrystalline graphene, or graphene quantum dots (GQDs).

In some embodiments, the forming the surface treatment layer may includeat least one of forming a hydrophobic surface treatment layer on thefirst material layer; and forming a hydrophilic surface treatment layeron the second material layer.

In some embodiments, the first material layer may include a metal, andthe second material layer may include an insulator or a semiconductor.

In some embodiments, the first material layer may include an insulatoror a semiconductor, and the second material layer may include a metal.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and effects of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIGS. 1 through 3 and 5 through 6 are diagrams for describing a methodof forming a carbon layer, according to an embodiment;

FIGS. 4A through 4C are example diagrams of Raman spectrums of intrinsicgraphene, nanocrystalline graphene, and an amorphous carbon layer;

FIGS. 7 and 8 are diagrams for describing a method of forming a carbonlayer, according to another embodiment;

FIGS. 9 through 22 are diagrams for describing a method of forming aninterconnect structure, according to an embodiment; and

FIGS. 23, 24A, and 24B are interconnect structures according to someembodiments.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments, examples of whichare illustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. In this regard, the presentembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein. Accordingly, theembodiments are merely described below, by referring to the figures, toexplain aspects. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items. Expressionssuch as “at least one of,” when preceding a list of elements, modify theentire list of elements and do not modify the individual elements of thelist. For example, “at least one of A, B, and C,” “at least one of A, B,or C,” “one of A, B, C, or a combination thereof,” and “one of A, B, C,and a combination thereof,” respectively, “may be construed as coveringany one of the following combinations: A; B; A and B; A and C; B and C;and A, B, and C.”

Embodiments will now be described more fully with reference to theaccompanying drawings, in which embodiments of the present disclosureare shown. In the drawings, like reference numerals denote likeelements, and sizes of the elements in the drawings may be exaggeratedfor clarity and convenience of description. Embodiments described hereinare examples only, and may include various modifications.

Throughout the specification, it will also be understood that when anelement is referred to as being “on” another element, it can be directlyon, under, on the left of, or on the right of the other element, orintervening elements may also be present. An expression used in thesingular encompasses the expression of the plural, unless it has aclearly different meaning in the context. It is to be understood thatthe terms such as “including”, etc., are intended to indicate theexistence of the components, and are not intended to preclude thepossibility that one or more other components may added.

The use of the terms “the” and similar referents in the context are tobe construed to cover both the singular and the plural.

The steps of all methods described herein can be performed in anysuitable order unless otherwise indicated herein or otherwise clearlycontradicted by context.

The use of any and all examples, or example language (e.g., “such as”)provided herein, is intended merely to better illuminate features ofinventive concepts and does not pose a limitation on the scope ofinventive concepts unless otherwise claimed.

FIGS. 1 through 3 and 5 through 6 are diagrams for describing a methodof forming a carbon layer, according to an embodiment.

Referring to FIG. 1 , a substrate 100 is provided. The substrate 100 mayinclude first and second material layers 110 and 120 having differentcharacteristics and/or different materials. The first material layer 110may include, for example, a metal. The metal may include, for example,at least one of Cu, Ru, Rh, Ir, Mo, W, Pd, Pt, Co, Ta, Ti, Ni, and Pd,but is not limited thereto.

The second material layer 120 may include, for example, an insulator ora semiconductor. The insulator may include, for example, silicon oxide,silicon nitride, SiOC, or boron nitride (BN), but is not limitedthereto. Also, the insulator may include a porous material. Thesemiconductor may include, for example, at least one of a Group IVmaterial, a Group III-V compound, and a Group II-VI compound, but is notlimited thereto.

Referring to FIG. 2 , surface treatment layers 131 and 132 are formed ona surface of the substrate 100. The surface treatment layers 131 and 132may be used to adjust surface energy of the substrate 100 to allow acarbon layer 140, which will be described later, to be selectivelyformed only on a hydrophobic surface of the substrate 100.

The surface treatment layers 131 and 132 may include a hydrophobicsurface treatment layer 131 formed on a surface of the first materiallayer 110 and a hydrophilic surface treatment layer 132 formed on asurface of the second material layer 120.

The hydrophobic surface treatment layer 131 may be formed as aself-assembled monolayer (SAM) on a surface of the first material layer110. The hydrophobic surface treatment layer 131 may have a relativelysmall thickness of about several nm, but is not limited thereto.

The hydrophobic surface treatment layer 131 may include an organicmaterial including a hydrophobic functional group. The hydrophobicfunctional group may include, for example, a fluorine group, a methylgroup, or a fluorinated alkyl group. However, the above is merely anexample.

The hydrophilic surface treatment layer 132 may be formed as an SAM on asurface of the second material layer 120. The hydrophilic surfacetreatment layer 132 may have a relatively small thickness of aboutseveral nm, but is not limited thereto.

The hydrophilic surface treatment layer 132 may include an organicmaterial including a hydrophilic functional group. The hydrophilicfunctional group may include a functional group capable of forming ahydrogen bond. For example, the hydrophilic functional group may includea hydroxyl group, a thiol group, or an amino group, but these are merelyexamples.

As described above, as the hydrophobic surface treatment layer 131 isformed on the first material layer 110 and the hydrophilic surfacetreatment layer 132 is formed on the second material layer 120, adifference in surface energy between the first material layer 110 andthe second material layer 120 may increase.

As the hydrophobic surface treatment layer 131 is formed on the firstmaterial layer 110 and the hydrophilic surface treatment layer 132 isformed on the second material layer 120, difference in contact anglesbetween the first material layer 110 and the second material layer 120may be, for example, about 50 degrees or greater, but is not limitedthereto. Here, a contact angle refers to a water contact angle (WCA),which applies the same below. A WCA refers to an angle in contact withwater drops on an air-liquid-solid interface.

Referring to FIG. 3 , the carbon layer 140 is formed on the firstmaterial layer 110, on which the hydrophobic surface treatment layer 131is formed. The carbon layer 140 includes carbon atoms having an sp²bonding structure. The carbon layer 140 having an sp² bonding structureis hydrophobic. Accordingly, the carbon layer 140 having an sp² bondingstructure may be selectively formed only on the first material layer110, on which the hydrophobic surface treatment layer 131 is formed, inthe substrate 100.

The carbon layer 140 having an sp² bonding structure may include, forexample, graphene or graphene quantum dots (GQD). Graphene refers to amaterial having a hexagonal honeycomb structure in which carbon atomsare connected two-dimensionally. Graphene may include intrinsic grapheneor nanocrystalline graphene. GQD refer to nano-sized graphene fragments.Each graphene fragment may have a disc shape having a thickness of aboutseveral nm or less (e.g., about 0.34 nm to about 100 nm, and/or about0.34 nm to about 50 nm, and/or about 0.34 nm to about 10 nm) and adiameter of about several to tens of nm (e.g., about 100 nm or less,about 70 nm or less, or about 30 nm or less), but is not limitedthereto.

Intrinsic graphene is also referred to as crystalline graphene and mayinclude crystals having a size greater than about 100 nm.Nanocrystalline graphene may include smaller crystals in size thanintrinsic graphene, for example, crystals having a size of, for example,about 100 nm or smaller.

Hereinafter, intrinsic graphene, nanocrystalline graphene, and anamorphous carbon layer will be compared in detail.

FIGS. 4A through 4C are example diagrams of Raman spectrums of intrinsicgraphene, nanocrystalline graphene, and an amorphous carbon layer. Aratio of carbons having an sp² bonding structure to all the carbons tobe described later may be obtained using, for example, an X-rayphotoelectron spectroscopy (XPS) analysis, and a content of hydrogen maybe obtained through Rutherford Backscattering Spectroscopy (RBS).

FIG. 4A is an example diagram of a Raman spectrum showing intrinsicgraphene.

Referring to FIG. 4A, in intrinsic graphene, which is crystallinegraphene, a ratio of D peak intensity to G peak intensity may be, forexample, less than about 0.1, and a ratio of 2D peak intensity to G peakintensity may be, for example, greater than about 2. The intrinsicgraphene may include crystals having a size greater than about 100 nm.

In intrinsic graphene, a ratio of carbons having an sp² bondingstructure to all the carbons may be nearly 100%. Also, intrinsicgraphene may hardly include hydrogen. In addition, a density ofintrinsic graphene may be, for example, about 2.1 g/cc, and a sheetresistance of intrinsic graphene may be, for example, about 100 Ohm/sqto about 1000 Ohm/sq, but is not limited thereto.

FIG. 4B is an example diagram of a Raman spectrum showingnanocrystalline graphene.

Referring to FIG. 4B, in nanocrystalline graphene, a ratio of aD-peak-intensity to a G-peak-intensity may be, for example, less thanabout 2.1, and a ratio of 2D-peak-intensity to the G-peak-intensity maybe, for example, greater than about 0.1. Also, a full width at halfmaximum (FWHM) of a D peak may be, for example, about 25 cm⁻¹ to 120cm⁻¹.

Nanocrystalline graphene may include crystals having a smaller size thanthose of intrinsic graphene, for example, crystals having a size ofabout 0.5 nm to about 100 nm. In nanocrystalline graphene, a ratio ofcarbons having an sp² bonding structure to all the carbons may be, forexample, about 50% to about 99%. Also, nanocrystalline graphene mayinclude hydrogen in, for example, about 1 at % to about 20 at %. Inaddition, a density of nanocrystalline graphene may be, for example,about 1.6 g/cc to about 2.1 g/cc, and a sheet resistance ofnanocrystalline graphene may be, for example, about 1000 Ohm/sq.

FIG. 4C is an example diagram of a Raman spectrum showing an amorphouscarbon layer.

Referring to FIG. 4C, an FWHM of an amorphous carbon layer at a D-peakmay be, for example, greater than about 120 cm⁻¹. In an amorphous carbonlayer, a ratio of carbons having an sp² bonding structure to all thecarbons may be, for example, about 30% to about 50%. Also, an amorphouscarbon layer may include hydrogen of a content greater than about 20atomic percent (at %).

Referring back to FIG. 3 , the carbon layer 140 having an sp² bondingstructure may be selectively formed on the first material layer 110, onwhich a hydrophobic surface treatment layer 131 is formed, by usingdeposition, transfer, or solution coating.

For example, when the carbon layer 140 includes graphene, the carbonlayer 140 may be formed by depositing a graphene layer on the firstmaterial layer 110, on which the hydrophobic surface treatment layer 131is formed, by chemical vapor deposition (CVD) or plasma enhanced CVD(PECVD). Also, the carbon layer 140 may be formed by transferringgraphene to the first material layer 110, on which the hydrophobicsurface treatment layer 131 is formed.

When the carbon layer 140 includes GQDs, the carbon layer 140 may beformed by coating the first material layer 110, on which the hydrophobicsurface treatment layer 131 is formed, with a solution including GQDs,and drying the same.

The carbon layer 140 having an sp² bonding structure may have a contactangle greater than those of the first and second material layers 110 and120, and accordingly, the carbon layer 140 having an sp² bondingstructure may have lower surface energy than the first and secondmaterial layers 110 and 120. For example, a surface of the carbon layer140 having an sp² bonding structure may have a relatively large contactangle of about 60 degrees to about 110 degrees, but is not limitedthereto.

Referring to FIGS. 3 and 5 , the hydrophilic surface treatment layer 132formed on the second material layer 120 may be removed after the carbonlayer 140 having an sp² bonding structure is selectively formed on thefirst material layer 110, on which the hydrophobic surface treatmentlayer 131 is formed. The hydrophilic surface treatment layer 132 may beremoved using a certain annealing process. In this process, at least aportion of the hydrophobic surface treatment layer 131 formed betweenthe first material layer 110 and the carbon layer 140 may be degraded.

Referring to FIG. 6 , a third material layer 150 may be selectivelyformed on the second material layer 120 after removing hydrophilicsurface treatment layer 132. The carbon layer 140 having an sp² bondingstructure has lower surface energy than the second material layer 120,and thus, the carbon layer 140 may act as a mask when forming the thirdmaterial layer 150. Accordingly, the third material layer 150 may beselectively formed only on a surface of the second material layer 120.The third material layer 150 may include, for example, an insulator.Examples of the insulator may include Al₂O₃, AlN, ZrO₂, HfO_(x), SiO₂,SiCO, SiCN, SiON, SiCOH, AlSiO, and BN, but are not limited thereto.

Above, as a method to increase a difference in surface energy betweenthe first material layer 110 and the second material layer 120, formingthe hydrophobic surface treatment layer 131 and the hydrophilic surfacetreatment layer 132 respectively on the first and second material layers110 and 120 has been described. However, as a method to increase adifference in surface energy between the first material layer 110 andthe second material layer 120, alternatively, the hydrophobic surfacetreatment layer 131 may be formed only on the first material layer 110and no surface treatment layer may be formed on the second materiallayer 120 or the hydrophilic surface treatment layer 132 may be formedonly on the second material layer 120 and no surface treatment layer maybe formed on the first material layer 110.

When the hydrophobic surface treatment layer 131 is formed only on thefirst material layer 110, a difference in contact angles between asurface of the first material layer 110, on which the hydrophobicsurface treatment layer 131 is formed, and a surface of the secondmaterial layer 120 where no surface treatment layer is formed may beabout 50 degrees or greater. Also, when the hydrophilic surfacetreatment layer 132 is formed only on the second material layer 120, adifference in contact angles between a surface of the first materiallayer 110, on which no surface treatment layer is formed, and a surfaceof the second material layer 120, on which the hydrophilic surfacetreatment layer 132 is formed, may be about 50 degrees or greater.

FIGS. 7 and 8 are diagrams for describing a method of forming a carbonlayer, according to another embodiment.

Referring to FIG. 7 , a hydrophilic surface treatment layer 132′ isformed on the first material layer 110 of the substrate 100, and ahydrophobic surface treatment layer 131′ is formed on the secondmaterial layer 120 of the substrate 100. The first and second materiallayers 110 and 120 are described above. Unlike the above-describedembodiment, in the present embodiment, the hydrophilic surface treatmentlayer 132′ is formed on the first material layer 110, and thehydrophobic surface treatment layer 131′ is formed on the secondmaterial layer 120. The hydrophobic surface treatment layer 131′ and thehydrophilic surface treatment layer 132′ are described above, and thus,description thereof will be omitted.

Referring to FIG. 8 , a carbon layer 140′ having an sp² bondingstructure is formed on the second material layer 120, on which thehydrophobic surface treatment layer 131′ is formed. The carbon layer140′ may include, for example, graphene or GQDs. The carbon layer 140′has low surface energy, and thus, may be selectively formed only on thesecond material layer 120, on which the hydrophobic surface treatmentlayer 131′ is formed, in the substrate 100. The carbon layer 140′ may beformed by deposition, transfer or solution coating.

According to the embodiments above, when the substrate 100 includes thefirst and second material layers 110 and 120 having differentcharacteristics, the hydrophobic surface treatment layer 131 or 131′ isformed on one of the first and second material layers 110 and 120, andthe hydrophilic surface treatment layer 132 or 132′ is formed on theother, thereby increasing a difference in surface energy between thefirst material layer 110 and the second material layer 120. Accordingly,the carbon layer 140 or 140′ having an sp² bonding structure having lowsurface energy may be selectively formed only on one of the first andsecond material layers 110 and 120, on which the hydrophobic surfacetreatment layer 131 or 131′ is formed.

Hereinafter, a method of forming an interconnect structure by using thecarbon layer having an sp² bonding structure, as a mask, will bedescribed.

FIGS. 9 through 22 are diagrams for describing a method of forming aninterconnect structure, according to an embodiment. In FIGS. 9 through22 , a method of forming an interconnect structure by using afully-aligned via (FAV) integration process is illustrated.

Referring to FIG. 9 , a substrate 200 is provided. The substrate 200 mayinclude a first insulating layer 220 and at least one first metal layer210. In FIG. 9 , an example in which two first metal layers 210 areapart from each other in the first insulating layer 220 is illustrated.

The first insulating layer 220 may typically include a low-k dielectricmaterial as an inter-metal dielectric (IMD). In detail, for example, thefirst insulating layer 220 may include a dielectric material having adielectric constant of about 3.6 or lower.

The first metal layers 210 provided in the first insulating layer 220may be conductive wirings. The first metal layers 210 may have, forexample, a nano-scale line width, but are not limited thereto. The firstmetal layers 210 may include, for example at least one of Cu, Ru, Rh,Ir, Mo, W, Pd, Pt, Co, Ta, Ti, Ni, and Pd, but is not limited thereto.

In FIG. 10 , a substrate 300 according to another example isillustrated. Referring to FIG. 10 , at least one first metal layer 310is provided in a first insulating layer 320, and a barrier layer 330 isbetween the first metal layer 310 and the first insulating layer 320.The first insulating layer 320 and the first metal layer 310 aredescribed above and may have different materials, and thus, descriptionthereof will be omitted.

The barrier layer 330 may limit and/or prevent diffusion of a materialof the first metal layer 310. The barrier layer 330 may have asingle-layer structure or a multi-layer structure in which multiplelayers including different materials from each other are stacked. Thebarrier layer 330 may include, for example, a metal, a metal alloy, or ametal nitride. In detail, for example, the barrier layer 330 may includeTa, Ti, Ru, RuTa, IrTa, W, TaN, TiN, RuN, IrTaN, TiSiN, Co, Mn, MnO orWN, but is not limited thereto. For example, the barrier layer 330 mayinclude nanocrystalline graphene.

A liner layer 335 for improving adhesion between the first metal layer310 and the barrier layer 330 may be further provided between the firstmetal layer 310 and the barrier layer 330. In some embodiments, theliner layer 335 may include a titanium nitride (TiN), titanium tungsten(TiW), tungsten nitride (WN), tantalum nitride (TaN), Ti, Ta, or acombination thereof. The barrier layer 330 and liner layer 335 may bedifferent materials.

Referring to FIG. 11 , surface treatment layers 231 and 232 are formedon a surface of the substrate 200 illustrated in FIG. 9 . The surfacetreatment layers 231 and 232 may be used to adjust a difference insurface energy between the first insulating layer 220 and the firstmetal layer 210 to allow a carbon layer 240, which will be describedlater, to be selectively formed only on the first metal layer 210 of thesubstrate 100. The surface treatment layers 231 and 232 may include ahydrophobic surface treatment layer 231 formed on the first metal layer210 and a hydrophilic surface treatment layer 232 formed on the firstinsulating layer 220.

The hydrophobic surface treatment layer 231 may be formed on a surfaceof the first metal layer 210 as an SAM, and may have a thickness ofabout several nm. The hydrophobic surface treatment layer 231 mayinclude an organic material including a hydrophobic functional group.For example, the hydrophobic functional group may include, for example,a fluorine group, a methyl group, or a fluorinated alkyl group, but isnot limited thereto.

The hydrophilic surface treatment layer 232 may be formed on a surfaceof the first insulating layer 220 as an SAM, and may have a thickness ofabout several nm. The hydrophilic surface treatment layer 232 mayinclude an organic material including a hydrophilic functional group.The hydrophilic functional group may include a functional group capableof forming a hydrogen bond. For example, the hydrophilic functionalgroup may include a hydroxyl group, a thiol group, or an amino group,but is not limited thereto.

As the hydrophobic surface treatment layer 231 is formed on the firstmetal layer 210, and the hydrophilic surface treatment layer 232 isformed on the first insulating layer 220, a difference in surface energybetween the first metal layer 210, on which the hydrophobic surfacetreatment layer 231 is formed, and the first insulating layer 220, onwhich the hydrophilic surface treatment layer 232 is formed, may beincreased.

A difference in contact angles between the first metal layer 210, onwhich the hydrophobic surface treatment layer 231 is formed, and thefirst insulating layer 220, on which the hydrophilic surface treatmentlayer 232 is formed, may be, for example, about 50 degrees or greater,but is not limited thereto.

While an embodiment in which the hydrophobic surface treatment layer 231is formed on the first metal layer 210 and the hydrophilic surfacetreatment layer 232 is formed on the first insulating layer 220 isdescribed above, the hydrophobic surface treatment layer 231 may beformed only on the first metal layer 210 and no surface treatment layermay be formed on the first insulating layer 220 or the hydrophilicsurface treatment layer 232 may be formed only on the first insulatinglayer 220 and no surface treatment layer may be formed on the firstmetal layer 210.

Referring to FIG. 12 , the carbon layer 240 is formed on each of thefirst metal layers 210, on which the hydrophobic surface treatment layer231 is formed. The carbon layer 240 includes carbon atoms having an sp²bonding structure. The carbon layer 240 having an sp² bonding structureis hydrophobic. Accordingly, the carbon layer 240 having an sp² bondingstructure may be selectively formed only on the first metal layer 210,on which the hydrophobic surface treatment layer 231 is formed, in thesubstrate 200.

The carbon layer 240 having an sp² bonding structure may include, forexample, intrinsic graphene, nanocrystalline graphene, or GQDs.Intrinsic graphene may include crystals having a size greater than about100 nm, and nanocrystalline graphene may include crystals having a sizeequal to or smaller than about 100 nm. Also, GQDs refer to nano-sizedgraphene fragments, and each graphene fragment may have a disc shapehaving a thickness of about several nm or less and a diameter of aboutseveral to tens of nm.

The carbon layer 240 having an sp² bonding structure may be selectivelyformed on the first metal layers 210, on which the hydrophobic surfacetreatment layer 231 is formed, by deposition transfer, or solutioncoating. When the carbon layer 240 includes graphene, the carbon layer240 may be formed on the first metal layers 210, on which thehydrophobic surface treatment layer 231 is formed, by deposition such asCVD or PECVD or transfer. Also, when the carbon layer 240 includes GQDs,the carbon layer 240 may be formed by solution coating.

The carbon layer 240 having an sp² bonding structure has a greatercontact angle than the first insulating layer 220 or the first metallayer 210. This indicates that the carbon layer 240 having an sp²bonding structure has a stable surface having lower surface energy thanthe first insulating layer 220 or the first metal layer 210. Forexample, a surface of the carbon layer 240 having an sp² bondingstructure may have a relatively large contact angle of about 60 degreesto about 110 degrees, but is not limited thereto.

According to a result of an experiment regarding contact angles, acontact angle of an IMD was measured to be about 34.8 degrees, andcontact angles of Cu and Ru were measured to be about 36.7 degrees andabout 29.2 degrees, respectively. In comparison to this, a contact angleof nanocrystalline graphene was measured to be about 90.6 degrees.

As described above, the carbon layer 240 having an sp² bonding structureand formed on the hydrophobic surface treatment layer 231 has a stablesurface having low surface energy, and thus, the carbon layer 240 mayact as a mask in a process to be described later, and accordingly, asecond insulating layer 250 (FIG. 12 ) may be selectively formed only onthe first insulating layer 220 between the carbon layers 240.

Meanwhile, the carbon layer 240 having an sp² bonding structure mayfurther include atoms having high electronegativity to further reducesurface energy. For example, the carbon layer 240 may further include F,Cl, Br, N, P or O atoms. In this case, the carbon layer 240 may have ahigher contact angle than when the above-described atoms are not added.For example, a contact angle of nanocrystalline graphene including Fatoms was measured to be about 102.1 degrees.

After the carbon layer 240 having an sp² bonding structure isselectively formed on the first metal layers 210, on which thehydrophobic surface treatment layer 231 is formed, the hydrophilicsurface treatment layer 232 formed on the first insulating layer 220 maybe removed by annealing or the like. In this process, at least a portionof the hydrophobic surface treatment layer 231 formed between the firstmetal layer 210 and the carbon layer 240 may be degraded.

In FIGS. 13 and 14 , carbon layers 341 and 342 having an sp² bondingstructure are selectively formed on the substrate 300 illustrated inFIG. 10 .

Referring to FIG. 13 , the carbon layer 341 having an sp² bondingstructure may be formed to cover only the first metal layer 310 of thesubstrate 300. In this case, a hydrophobic surface treatment layer 331may be formed on a surface of the first metal layer 310, and ahydrophilic surface treatment layer 332 may be formed on surfaces of thefirst insulating layer 320, the barrier layer 330, and the liner layer335.

Referring to FIG. 14 , the carbon layer 342 having an sp² bondingstructure may be formed to cover the first metal layer 310 and thebarrier layer 330 of the substrate 300. In this case, the hydrophobicsurface treatment layer 331 may be formed on surfaces of the first metallayer 310, the liner layer 335, and the barrier layer 330, and thehydrophilic surface treatment layer 332 may be formed on a surface ofthe first insulating layer 320.

Referring to FIG. 15 , the second insulating layer 250 may beselectively formed on the first insulating layer 220 from which thehydrophilic surface treatment layer 232 is removed. The secondinsulating layer 250 may be deposited on the first insulating layer 220by atomic layer deposition (ALD), CVD, or the like.

As described above, the carbon layer 240 having an sp² bonding structureand formed on the first metal layer 210 has a stable surface havinglower surface energy compared to the first insulating layer 220, andthus, the carbon layer 240 may act as a mask in a deposition process ofthe second insulating layer 250. Accordingly, the second insulatinglayer 250 may be selectively deposited only on the first insulatinglayer 220 between the carbon layers 240. In addition, the carbon layer240 having an sp² bonding structure is thermally stable even at a hightemperature of about 400° C. to about 500° C., and thus, the carbonlayer 240 may stably serve as a mask in ALD or CVD performed at a hightemperature.

As described above, the first insulating layer 220 may include, forexample, a low-k dielectric material, whereas the second insulatinglayer 250 may include a dielectric material having various dielectricconstants. For example, the second insulating layer 250 may includeAl₂O₃, AlN, ZrO₂, HfO_(x), SiO₂, SiCO, SiCN, SiON, SiCOH, AlSiO, or BN,is not limited thereto.

FIG. 16 illustrates an example of a result of measuring an Al2p peakemitted from a substrate including an IMD and nanocrystalline grapheneby using XPS, wherein an Al₂O₃ thin film is deposited on the substrateby using ALD.

In FIG. 16 , “A” denotes Al2p peaks emitted from the IMD, and “B”denotes Al2p peaks emitted from the nanocrystalline graphene. Referringto FIG. 16 , a rate at which an Al₂O₃ thin film is deposited on thenanocrystalline graphene was measured to be about 22.5% of a rate atwhich an Al₂O₃ thin film is deposited on the IMD. This indicates that anAl₂O₃ thin film may be selectively deposited on the IMD instead of thenanocrystalline graphene.

FIG. 17 illustrates an example of a Raman spectrum of nanocrystallinegraphene, measured before and after annealing performed during ALD, whenan Al₂O₃ thin film is deposited, by using ALD, on a substrate includingan IMD and nanocrystalline graphene.

Referring to FIG. 17 , almost the same Raman spectrum was measuredbefore and after annealing. The result of the experiment above indicatesthat a carbon layer having an sp² bonding structure may act as a maskwhile being hardly affected by annealing performed in a process ofdepositing a second insulating layer.

Referring to FIG. 18 , after forming a third insulating layer 260covering the second insulating layer 250 and the carbon layer 240 havingan sp² bonding structure, the third insulating layer 260 is patterned toform a via hole 255 to expose the carbon layer 240. The third insulatinglayer 260 may be an IMD.

Referring to FIG. 19 , the carbon layer 240 exposed through the via hole255 may be removed. Removal of the carbon layer 240 may be performed byetching or ashing. For example, the carbon layer 240 may be removedusing oxygen (O₂) plasma) or hydrogen (H₂) plasma). When the carbonlayer 240 having an sp² bonding structure is completely removed, thefirst metal layer 210 of the substrate 200 may be exposed through thevia hole 255.

In FIG. 19 , an embodiment in which the carbon layer 240 having an sp²bonding structure and formed on the first metal layer 210 is completelyremoved is described. However, in other embodiments, the carbon layer240 formed on the first metal layer 210 may not be removed, and mayremain on the first metal layer 210.

In addition, as illustrated in FIG. 20 , only a portion of the carbonlayer 240 having an sp² bonding structure and formed on some of thefirst metal layers 210 may be removed. The carbon layer 240 having ansp² bonding structure and remaining on the first metal layer 210 may actas a capping layer in an interconnect structure. The capping layerdescribed above may reduce electrical resistance of the first metallayer 210, thus increasing electromigration resistance.

Recently, for high level of integration of semiconductor devices, thesize of semiconductor devices has been gradually decreasing, andaccordingly, a line width of conductive wirings is also reduced.However, when the line width of conductive wirings is reduced, a currentdensity in the conductive wirings is increased, thereby increasingelectrical resistance of the conductive wirings. The increase inelectrical resistance leads to electromigration to cause a defect in theconductive wirings, and this may damage the conductive wirings. Here,the electromigration refers to movement of a substance by continuousmovement of ions in a conductor, wherein the movement of ions isgenerated by the transfer of momentum between conductive electrons andatomic nuclei in a metal.

As described above, by leaving all or a portion of the carbon layer 240having an sp² bonding structure and formed on the first metal layer 210,instead of removing the same, the carbon layer 240 left may act as acapping layer that is capable of increasing electromigration resistance.

FIG. 21 is an example of a Raman spectrum showing a result of performingan ashing process on nanocrystalline graphene formed on a substrate, byusing hydrogen plasma. In FIG. 21 , Raman spectrums before performing anashing process and after performing an ashing process for 10 minutes, 20minutes, and 30 minutes, respectively, are shown.

Referring to FIG. 21 , the longer a hydrogen plasma process isperformed, an amount of nanocrystalline graphene formed on the substrategradually decreases. Accordingly, by adjusting a period of time ofperforming the hydrogen plasma process, an amount of nanocrystallinegraphene left on the substrate may be adjusted.

Referring to FIG. 22 , a fourth insulating layer 270 is formed to fillthe via hole 255, and then the fourth insulating layer 270 is patternedto form a second metal layer 280 that is electrically connected to thefirst metal layer 210. The fourth insulating layer 270 may be an IMD.

When at least a portion of the carbon layer 240 formed on the firstmetal layer 210 is not removed but left, there may be the carbon layer240 between the first metal layer 210 and the second metal layer 280, asdepicted in FIG. 23 .

Above, an embodiment in which the third insulating layer 260 is formedto cover the carbon layer 240 and the second insulating layer 250 andthen the carbon layer 240 exposed through the via hole 255 formed bypatterning the third insulating layer 260 is removed is described.However, alternatively, the carbon layers 240 may be removed while inthe state as illustrated in FIG. 15 , and then the third insulatinglayer 260 may be formed and patterned to form a via hole exposing thefirst metal layer 210.

As described above, when forming an interconnect structure by using anFAV integration process, by forming the surface treatment layers 231 and232, through which surface energy may be adjusted, on a surface of thesubstrate 200 including the first metal layer 210 and the firstinsulating layer 220, the carbon layer 240 having an sp² bondingstructure may be selectively formed only on the first metal layer 210.Also, by using the carbon layer 240 as a mask in a deposition process ofthe second insulating layer 250, the second insulating layer 250 may beselectively deposited only on the first insulating layer 220 between thecarbon layers 240.

FIGS. 15, 18-20, and 22 illustrate an example where operations of themethod of forming an interconnect structure are applied to the substrate200 in FIGS. 9-12 , but example embodiments are not limited thereto. Oneof ordinary skill in the art would appreciate that the operations inFIGS. 15, 18-20, and 22 alternatively may be applied to the substrate300 including the carbon layer 341 or the carbon layer 342 in FIG. 13 orFIG. 14 , respectively.

For example, referring to FIGS. 13 and 24A, an interconnect structureaccording to an embodiment may be formed by selectively forming a secondinsulating layer 250 only on the first insulating layer 320, barrierlayer 330, and liner layer 335 after the hydrophilic surface treatmentlayer 332 is removed. Then, the third insulating layer 260 covering thesecond insulating layer 250 may be formed and patterned to provide a viahole like the via hole 255 shown in FIG. 18 . Then, a fourth insulatinglayer 270 and second metal layer 280 may be formed on the thirdinsulating layer 260, second insulating layer 250, and carbon layer 341.The second metal layer 280 may be electrically connected to the firstmetal layer 210 through the via hole. Alternatively, although not shown,a portion of the carbon layer 341 may remain between the second metallayer 280 and first metal layer 210.

Additionally, for example, referring to FIGS. 13 and 24B, aninterconnect structure according to an embodiment may be formed byselectively forming a second insulating layer 250 only on the firstinsulating layer 320 after the hydrophilic surface treatment layer 332is removed. Then, the third insulating layer 260 covering the secondinsulating layer 250 may be formed and patterned to provide a via holelike the via hole 255 shown in FIG. 18 . Then, a fourth insulating layer270 and metal layer 280 may be formed on the third insulating layer 260,second insulating layer 250, and carbon layer 342. The metal layer 280may be electrically connected to the first metal layer 210.Alternatively, although not shown, a portion of the carbon layer 343 mayremain between the metal layer 280 and first metal layer 210.

As described above, according to example embodiments, by forming asurface treatment layer through which surface energy may be adjusted, ona surface of a substrate including first and second material layershaving different characteristics, a carbon layer having an sp² bondingstructure and a stable surface having low surface energy may beselectively formed on only one of the first and second material layers.

According to other embodiments, when forming an interconnect structureby using an FAV integration process, by forming a surface treatmentlayer through which surface energy may be adjusted, on a surface of asubstrate including a first metal layer and a first insulating layer, acarbon layer having an sp² bonding structure may be selectively formedonly on the first metal layer. Also, by using the carbon layer as a maskin a deposition process of a second insulating layer, the secondinsulating layer may be selectively deposited only on the firstinsulating layer between the carbon layers.

It should be understood that embodiments described herein should beconsidered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments. While one or more embodiments have beendescribed with reference to the figures, it will be understood by thoseof ordinary skill in the art that various changes in form and detailsmay be made therein without departing from the spirit and scope ofinventive concepts as defined by the following claims.

What is claimed is:
 1. A method of forming a carbon layer, the methodcomprising: providing a substrate including a first material layer and asecond material layer; forming a surface treatment layer on at least oneof the first material layer and the second material layer; andselectively forming a carbon layer on a portion of the surface treatmentlayer on the at least one of the first material layer and the secondmaterial layer, the carbon layer having an sp² bonding structure.
 2. Themethod of claim 1, wherein the surface treatment layer forms ahydrophobic surface on the first material layer and a hydrophilicsurface on the second material layer, and the selectively forming thecarbon layer forms the carbon layer over the hydrophobic surface on thefirst material layer.
 3. The method of claim 1, wherein the carbon layercomprises intrinsic graphene, nanocrystalline graphene, or graphenequantum dots (GQDs).
 4. The method of claim 1, wherein the forming thesurface treatment layer includes forming the surface treatment layer asa self-assembled monolayer (SAM).
 5. The method of claim 1, wherein,after the forming the surface treatment layer, a difference between awater contact angle (WCA) of the first material layer and a WCA of thesecond material layer is 50 degrees or greater.
 6. The method of claim1, wherein the forming the surface treatment layer comprises at leastone of: forming a hydrophobic surface treatment layer on one of thefirst material layer or the second material layer; and forming ahydrophilic surface treatment layer on an other of the first materiallayer or the second material layer.
 7. The method of claim 6, whereinthe hydrophobic surface treatment layer comprises an organic materialincluding a hydrophobic functional group.
 8. The method of claim 6,wherein the hydrophilic surface treatment layer comprises an organicmaterial including a hydrophilic functional group.
 9. The method ofclaim 8, wherein the hydrophilic functional group comprises a functionalgroup capable of forming a hydrogen bond.
 10. The method of claim 1,wherein the first material layer comprises a metal, and the secondmaterial layer comprises an insulator or a semiconductor.
 11. The methodof claim 1, wherein the selectively forming the carbon layer isperformed using deposition, transfer, or solution coating.
 12. Themethod of claim 1, further comprising: selectively forming a thirdmaterial layer on the first material layer or the second material layer,wherein the third material layer is formed on the one of the firstmaterial layer and the second material layer on which the carbon layeris not formed.
 13. The method of claim 1, wherein the first materiallayer comprises an insulator or a semiconductor, and, the secondmaterial layer comprises a metal.
 14. A method of forming aninterconnect structure, the method comprising: providing a substrateincluding a first metal layer and a first insulating layer; forming asurface treatment layer on at least one of the first metal layer and thefirst insulating layer; and selectively forming a carbon layer on thefirst metal layer, the carbon layer having an sp² bonding structure;selectively forming a second insulating layer on the first insulatinglayer; forming a third insulating layer to cover the second insulatinglayer; and forming a second metal layer after the forming the thirdinsulating layer, the second metal layer being electrically connected tothe first metal layer.
 15. The method of claim 14, wherein the carbonlayer comprises intrinsic graphene, nanocrystalline graphene, orgraphene quantum dots (GQDs).
 16. The method of claim 14, wherein thefirst insulating layer comprises a dielectric material having adielectric constant of 3.6 or lower.
 17. The method of claim 14, whereinthe carbon layer has a contact angle of about 60 degrees to about 110degrees.
 18. The method of claim 14, wherein the carbon layer furthercomprises F, CL, Br, N, P or O atoms.
 19. The method of claim 14,wherein the second insulating layer comprises Al₂O₃, AlN, ZrO₂, HfO_(x),SiO₂, SiCO, SiCN, SiON, SiCOH, AlSiO, or BN.
 20. The method of claim 14,wherein at least a portion of the carbon layer remains on the firstmetal layer after the forming the second metal layer.
 21. The method ofclaim 14, further comprising: removing a portion of the carbon layer orremoving all of the carbon layer.
 22. A method of forming a carbonlayer, the method comprising: forming a surface treatment layer on asubstrate, the substrate including a first material layer and a secondmaterial layer, a material of the first material layer being differentthan a material of the second material layer, the surface treatmentlayer on the first material layer; and selectively forming a carbonlayer on the surface treatment layer on the first material layer and notthe second material layer, the carbon layer having an sp² bondingstructure.
 23. The method of claim 22, wherein the carbon layercomprises intrinsic graphene, nanocrystalline graphene, or graphenequantum dots (GQDs).
 24. The method of claim 22, wherein the forming thesurface treatment layer comprises at least one of: forming a hydrophobicsurface treatment layer on the first material layer; and forming ahydrophilic surface treatment layer on the second material layer. 25.The method of claim 22, wherein the first material layer comprises ametal, and the second material layer comprises an insulator or asemiconductor.